Mechanical Seal Including Recovery Port For Use With Pumps

ABSTRACT

A mechanical seal for an axial flow pump may include an annular seal housing configured to be received in a pump housing, the annular seal housing defining a shaft aperture configured for passage therethrough by a pump shaft of the axial flow pump. The annular seal housing may include a second seal housing face at least partially defining an annular first seal recess having a first inner diameter and configured to receive therein an annular stationary seal, such that the annular stationary seal provides a stationary seal against the pump shaft, an annular face seal recess having a second inner diameter greater than the first inner diameter and configured to receive therein a stationary face seal, and a recovery port extending from one or more of the first seal recess or the face seal recess to an exterior of the annular seal housing.

PRIORITY CLAIM

This U.S. non-provisional patent application claims priority to and thebenefit of, under 35 U.S.C. § 119(e), U.S. Provisional Application No.63/084,224, filed Sep. 28, 2020, “Mechanical Seal Including RecoveryPort for Use with Pumps,” the disclosure of which is incorporated hereinby reference in its entirety.

TECHNICAL FIELD

The present disclosure relates to a mechanical seal for use with pumpsand, more particularly, to a mechanical seal including a recovery portfor use with pumps.

BACKGROUND

Pumps may be used to transfer a fluid from one receptacle to anotherlocation. For example, a barge may include an interior cavity, which mayinclude one or more tanks containing a fluid or fluid-like material fortransport via waterways or bodies of water. Pumps may be used to pumpthe fluid or fluid-like material from the one or more tanks into anothercontainer for storage or transport over land. Some pumps may include apump shaft for driving one or more impellers to cause flow of the fluidthrough the pump. The pump shaft may be rotationally supported by one ormore bearings. A seal may be provided to prevent fluid being pumped fromleaking around the pump shaft. The seal may be prone to leak,particularly following an extended service period during which internalcomponents of the seal may wear. Because barges often transportmaterials that are not considered environmentally friendly, such aschemicals and fuels, signs of leakage may result in an unanticipatedneed to service or replace a pump seal at remote locations due to themobile nature of barges. This may lead to missed delivery dates, costlyoff-site repairs, and other inefficiencies in a cargo transportationoperation.

Accordingly, it may be desirable to provide a seal for pumps thatmitigates or eliminates one or more of the foregoing and other relatedor unrelated, issues, and/or problems.

SUMMARY

In view of the foregoing, in one aspect, the present disclosure isdirected to a mechanical seal for use with pumps and, more particularly,to a mechanical seal including a recovery port for use with pumps. Insome embodiments, the mechanical seal may include a recovery portconfigured to provide a flow path away from the mechanical seal forfluid passing through the mechanical seal. The recovery port may becoupled to a fluid line for providing flow communication between therecovery port and a location away from the mechanical seal, such as backtoward a pump inlet, so that the fluid may be pumped to a desiredlocation or tank. In some embodiments, the recovery port may reduce thelikelihood or prevent fluid being pumped by the pump from being releasedinto the atmosphere or away from the barge.

According to one aspect, a mechanical seal for an axial flow pump mayinclude an annular seal housing configured to be received in a pumphousing, the annular seal housing defining a shaft aperture configuredfor passage therethrough by a pump shaft of the axial flow pump. Theannular seal housing may include a first seal housing face and a secondseal housing face opposite the first seal housing face and at leastpartially defining an annular first seal recess having a first innerdiameter and configured to receive therein an annular stationary seal,such that the annular stationary seal provides a stationary seal againstthe pump shaft. The second seal housing face may further at leastpartially define an annular face seal recess having a second innerdiameter greater than the first inner diameter and configured to receivetherein a stationary face seal. The second seal housing face may also atleast partially define a recovery port extending from one or more of thefirst seal recess or the face seal recess to an exterior of the annularseal housing. The mechanical seal may also include a stationary sealreceived in the annular first seal recess and a stationary face sealreceived in the annular face seal recess. The mechanical seal mayfurther include an inner sleeve coupled to the annular seal housing andconfigured to receive therethrough the pump shaft and rotate with thepump shaft, such that the inner sleeve rotates relative to the annularseal housing. The inner sleeve may include a substantially hollowcylindrical body defining an internal recess configured to receivetherein a shaft seal configured to abut the pump shaft and rotate withthe pump shaft. The mechanical seal may still further include a rotatingface seal retainer configured to receive therein a rotating face seal,and a rotating face seal received in the rotating face seal retainer andconfigured to abut against the stationary face seal and rotate with thepump shaft, such that the stationary face seal and the rotating faceseal form a sliding seal interface. The mechanical seal may furtherinclude a biasing member positioned to press the rotating face sealagainst the stationary face seal.

According to a further aspect, an axial flow pump and mechanical sealassembly may include an axial flow pump configured to pump fluid. Theaxial flow pump may include a longitudinal containment chamber, and apump shaft extending longitudinally within the containment chamber. Theaxial flow pump may further include at least one pump housing coupled toan entry end of the pump shaft, such that the pump shaft rotatesrelative to the pump housing. The axial flow pump may also include atleast one impeller coupled to the pump shaft and configured to rotatewith the pump shaft. The axial flow pump may also include a dischargepassage at a discharge end of the axial flow pump opposite the entry endof the pump shaft. The assembly may further include a mechanical sealcoupled to the pump shaft opposite the entry end of the pump shaftrelative to discharge passage. The mechanical seal may include anannular seal housing received in a pump housing. The annular sealhousing may define a shaft aperture through which the pump shaft of theaxial flow pump passes. The annular seal housing may include a firstseal housing face and a second seal housing face opposite the first sealhousing face and at least partially defining an annular first sealrecess having a first inner diameter and configured to receive thereinan annular stationary seal, such that the annular stationary sealprovides a stationary seal against the pump shaft. The second sealhousing face may further at least partially define an annular face sealrecess having a second inner diameter greater than the first innerdiameter and configured to receive therein a stationary face seal. Thesecond seal housing face may still further at least partially define arecovery port extending from one or more of the first seal recess or theface seal recess to an exterior of the annular seal housing. Themechanical seal may further include a stationary seal received in theannular first seal recess, and a stationary face seal received in theannular face seal recess. The mechanical seal may further include aninner sleeve coupled to the annular seal housing and receivingtherethrough the pump shaft and configured to rotate with the pumpshaft, such that the inner sleeve rotates relative to the annular sealhousing. The inner sleeve may include a substantially hollow cylindricalbody defining an internal recess configured to receive therein a shaftseal configured to abut the pump shaft and rotate with the pump shaft.The mechanical seal may also include a rotating face seal retainerconfigured to receive therein a rotating face seal, and a rotating faceseal received in the rotating face seal retainer and configured to abutagainst the stationary face seal and rotate with the pump shaft, suchthat the stationary face seal and the rotating face seal form a slidingseal interface. The mechanical seal may further include a biasing memberpositioned to press the rotating face seal against the stationary faceseal.

These and other advantages and aspects of the embodiments of thedisclosure will become apparent and more readily appreciated from thefollowing detailed description of the embodiments and the claims, takenin conjunction with the accompanying drawings. Moreover, it is to beunderstood that both the foregoing summary of the disclosure and thefollowing detailed description are exemplary and intended to providefurther explanation without limiting the scope of the disclosure asclaimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the embodiments of the present disclosure, areincorporated in and constitute a part of this specification, illustrateembodiments of this disclosure, and together with the detaileddescription, serve to explain the principles of the embodimentsdiscussed herein. No attempt is made to show structural details of thisdisclosure in more detail than may be necessary for a fundamentalunderstanding of the exemplary embodiments discussed herein and thevarious ways in which they may be practiced.

FIG. 1 is a schematic perspective view of an example axial flow pumpassembly including an example axial flow pump and example mechanicalseal shown mounted to an example support structure according toembodiments of the disclosure.

FIG. 2 is a schematic top view of an axial flow pump including anexample input shaft for coupling to a prime mover to supply power to theaxial flow pump and an example discharge passage for discharging pumpedfluid according to embodiments of the disclosure.

FIG. 3 is a schematic side section view showing an example axial flowpump mounted to an example support structure and showing example flowpaths for fluid pumped by the axial flow pump according to embodimentsof the disclosure.

FIG. 4 is a partial schematic perspective view showing a portion of anexample axial flow pump including an example mechanical seal and anexample discharge passage for fluid pumped by the axial flow pumpaccording to embodiments of the disclosure.

FIG. 5 is a partial schematic perspective view from a different anglethan FIG. 4 showing a portion of an example axial flow pump including anexample mechanical seal according to embodiments of the disclosure.

FIG. 6 is a schematic partial side section view of a portion of anexample axial flow pump including an example mechanical seal and anexample discharge passage for fluid pumped by the axial flow pumpaccording to embodiments of the disclosure.

FIG. 7 is a schematic partial side section view of a portion an exampleaxial flow pump including an example mechanical seal including anexample recovery port and example vent ports according to embodiments ofthe disclosure.

DETAILED DESCRIPTION

The following description is provided as an enabling teaching ofembodiments of this disclosure. Those skilled in the relevant art willrecognize that many changes can be made to the embodiments described,while still obtaining the beneficial results. It will also be apparentthat some of the desired benefits of the embodiments described can beobtained by selecting some of the features of the embodiments withoututilizing other features. Accordingly, those who work in the art willrecognize that many modifications and adaptations to the embodimentsdescribed are possible and may even be desirable in certaincircumstances. Thus, the following description is provided asillustrative of the principles of the embodiments of the disclosure andnot in limitation thereof, since the scope of the disclosure is definedby the claims.

FIG. 1 is a schematic perspective view of an example axial flow pumpassembly 10 including an example axial flow pump 12 and examplemechanical seal 14 shown mounted to an example support structure 16according to embodiments of the disclosure. In some embodiments, theassembly 10 may be mounted on a deck or support of a waterborne vehicleconfigured to transport fluid or semi-fluid materials (e.g., liquid orsemi-liquid materials), such as a barge, and the axial flow pump 12 maybe used to pump or transfer fluid from an interior 18 of the of thewaterborne vehicle to another waterborne vehicle, to a land-bornevehicle, and/or into a container, such as a tank. In some embodiments,the axial flow pump 14 may include or be a vertical barge pump. As shownin FIG. 1, the assembly 10 may be mounted to the support structure 16,so that the axial flow pump 12 extends through a hole 20 in the supportstructure 16 and into the interior 18 of the waterborne vehicle. Asshown, some embodiments of the axial flow pump 14 may include a mountingflange 19 configured to be coupled to the support structure 16.

In some embodiments, one or more conduits between one or more holdingtanks in the waterborne vehicle may be coupled to the axial flow pump 12to provide fluid flow between the one or more holding tanks to the axialflow pump 12, so that the fluid or semi-fluid materials may betransferred from the interior of the waterborne vehicle to anotherwaterborne vehicle, to a land-borne vehicle, and/or into a container,for example, as described herein with respect to FIGS. 2 and 3.

FIG. 2 is a schematic top view of an axial flow pump 12 including anexample input shaft 22 for coupling to an output drive shaft 24 of aprime mover to supply power to the axial flow pump 12, and an exampledischarge passage 26 for discharging pumped fluid according toembodiments of the disclosure. For example, the prime mover may includeone or more of any type of internal combustion engine (e.g., a dieselengine or spark-ignition engine) and/or an electric motor configured togenerate mechanical power and torque to drive the input shaft 22 of theaxial flow pump 12. In the example embodiment shown in FIG. 2, the axialflow pump 12 may include a transmission 28 including one or more gearsconfigured receive power and torque from the input shaft 22 rotatingabout a first axis X1 and transfer the power and torque to rotate a pumpshaft 30 of the axial flow pump 12, which rotates about a second axis X2(see FIG. 3) at an angle relative to the first axis X1 (e.g., an angleof about ninety degrees).

FIG. 3 is a schematic side section view showing an example axial flowpump 12 mounted to an example support structure 16 and showing exampleflow paths for fluid pumped by the axial flow pump 12 according toembodiments of the disclosure. As shown in FIG. 3, in some embodiments,the axial flow pump 12 may include one or more input ports 32 that maybe coupled to one or more conduits 34, for example, between one or moreholding tanks in the waterborne vehicle. The one or more conduits 34 maybe coupled to the one or more input ports 32 to provide a flow path Ainto a longitudinal containment chamber 36 of the axial flow pump 12.

In the example embodiment shown in FIG. 3, the axial flow pump 12 mayinclude at least one pump housing 38 coupled to an entry end 40 of thepump shaft 30, such that the pump shaft 30 rotates relative to the atleast one pump housing 38. In some embodiments, the fluid or semi-fluidmaterial may enter the containment chamber 36 via the one or more inputports 32 and be drawn down the containment chamber 36 along a flow pathB to the entry end 40. Once the fluid or semi-fluid material enters theat least one pump housing 38 at the entry end 40, it may be may be drawnupward along a flow path C by rotation of one or more impellers 42mounted to the pump shaft 30 and driven by the input shaft 22 (see FIG.2). Thereafter, the fluid or semi-fluid material may be discharged viaone or more of the discharge passages 26, for example, at a longitudinallocation above the support structure 16, as shown in FIGS. 3 and 4.

As shown in FIG. 3, some embodiments of the axial flow pump 12 mayinclude a plurality of pump housings 38, including, for example, a basehousing 38A, a stator housing 38B, one or more separator housings 38C,and/or one or more impeller housings 38D. In some embodiments, the axialflow pump 12 may include one or more stators 44 configured to not rotatewith the pump shaft 30, for example, as shown in FIG. 3. In the exampleembodiment shown, the axial flow pump 12 includes two impellers 42A and42B coupled to the pump shaft 30 and configured to rotate with the pumpshaft 30 and pump fluid or semi-fluid material through the axial flowpump 12 and out the one or more discharge passages 26.

FIG. 4 is a partial schematic perspective view showing a portion of anexample axial flow pump 12 including an example mechanical seal 14 andan example discharge passage 26 for fluid pumped by the axial flow pump12 according to embodiments of the disclosure. As shown in FIG. 4, thedischarge passage 26 provides communication for the fluid or semi-fluidmaterial to flow out of an upper end of the pump housing 38E along aflow path D. As shown in FIG. 4, the pump shaft 30 extends through themechanical seal 14 and is coupled to a stabilizer shaft 46 via a shaftcoupler 48. The stabilizer shaft 46 may extend upward through a bearingand may provide stability to the pump shaft 30 as it rotates.

As shown in FIGS. 3 and 4, the discharge passage 26 may be defined by acurved pipe section 50 extending from the upper pump housing 38E andradially away from the pump shaft 30, with the pump shaft 30 passingthrough an aperture 52 in a wall 54 of the pipe section 50. FIG. 5 is apartial schematic perspective view from a different angle than FIG. 4showing the portion of the example axial flow pump 12, including theexample mechanical seal 14, and FIG. 6 is a schematic partial sidesection view of the portion of the example axial flow pump 12 shown inFIGS. 4 and 5.

As shown in FIGS. 4, 5, and 6, a tubular housing 56 may extend from anexterior surface of the pipe section 50 and enclose the aperture 52 inthe wall 54 of the pipe section 50, with the pump shaft 30 extendingthrough the tubular housing 56 and through the mechanical seal 14. Inthe example embodiment shown, the tubular housing 56 is received in anaperture 58 of a radially extending barrier 60 configured to support themechanical seal 16, with an outer circumference 62 of the barrier 60being coupled to an interior surface 64 of an outer housing 66. In someembodiments, for example, as shown in FIGS. 4-7, a seal cap 70 may beprovided to secure the mechanical seal 14 to the barrier 60, forexample, via one or more fasteners (e.g., screws and/or nuts and bolts)extending through apertures in a housing of the mechanical seal 14 andinto or through the barrier 60.

In some embodiments, as the fluid or semi-fluid materials are pumpedfrom the discharge passage 26, some of the material may pass through aclearance 68 between the pump shaft 30 and the aperture 52 in the wall54 of the pipe section 50, and into a space 72 partially defined by thetubular housing 56. The mechanical seal 14, in at least someembodiments, may be provided and configured to prevent (or at leastreduce the amount of) the material in the tubular housing 56 fromescaping or otherwise leaking out of the axial flow pump 12. Forexample, as shown in FIGS. 4, 5, and 6, material that passes throughand/or around the mechanical seal 14 may collect on top of the barrier60 in the outer housing 66. Collection of material at this location,particularly when excessive, may lead to an unanticipated need toservice or replace the mechanical seal at remote locations, for example,due to the mobile nature of waterborne vehicles, such as barges.

FIG. 7 is a schematic partial side section view of a portion an exampleaxial flow pump 12 including an example mechanical seal 14, including anexample recovery port 74 and an example vent port 76, according toembodiments of the disclosure. Although only a single recovery port 74is shown in FIGS. 6 and 7, some embodiments may include more than onerecovery port 74. Although FIG. 7 shows only a single vent port 76, morevent ports 76 are contemplated.

As shown in FIG. 7, as explained in more detail herein, some embodimentsof the recovery port 74 may extend radially away from the mechanicalseal 14 and provide a flow path F for material that passes through themechanical seal 14 to flow away from the mechanical seal 14 and reduceor prevent collection of the material on top of the barrier 66 in theouter housing 66. For example, as shown in FIGS. 4-7, the recovery port74 and/or the vent port 76 may be in flow communication with respectivefluid lines 78, which may extend the respective flow paths E and F to alocation exterior to the outer housing 66. In some embodiments, asshown, the fluid lines 78 may extend back toward the support structure16, and provide flow communication with an interior of the containmentchamber 36, for example, via the respective flow paths E and F, whichmay allow the material flowing through the fluid lines 78 to be drawnback into the axial flow pump 14 for discharge through the dischargepassage 26. In some embodiments, pressure in the containment chamber 36may be a vacuum pressure or negative absolute pressure, for example, dueto suction of the axial flow pump 14. As a result, the recovery port 74and/or the vent port 76 may be subject to a suction pressure, which mayassist with recovery of fluid in flow communication with the recoveryport 74 and/or the vent port 76. For example, the recovery port 74and/or the vent port 76 may be configured to be in flow communicationwith the containment chamber 36, and pressure in the containment chamber36 may be at a lower pressure than pressure at the discharge passage 26of the axial flow pump 14, which may result in a suction pressure at therecovery port 74 and/or the vent port 76. Other destinations for thematerial passing through the fluid lines 78 are contemplated. In thisexample manner, at least some (e.g., all) of the material that passesthrough the mechanical seal 14 may be carried away from the barrier 66and the interior of the outer housing 66. In some embodiments, this mayreduce instances of unanticipated service or replacement of themechanical seal 14, for example, when the mechanical seal 14 is leakingmaterial, for example, due to wear, as explained herein.

As shown in FIG. 7, in some embodiments, the mechanical seal 14 may becoupled to the pump shaft 30 opposite the entry end 40 of the pump shaft30 relative to discharge passage 26. In some embodiments, the mechanicalseal 14 may include an annular seal housing 80 received in the outerhousing 66 of the axial flow pump 12 (e.g., in annular recess 82 of theseal cap 70). In some embodiments, the annular seal housing 80 maydefine a shaft aperture 84 through which the pump shaft 30 of the axialflow pump 14 passes. In some embodiments, the annular seal housing 80may include a first seal housing face 86 and a second seal housing face88 opposite the first seal housing face 86. The second seal housing face88 may at least partially define an annular first seal recess 90 havinga first inner diameter and configured to receive therein an annularstationary seal 92, such that the annular stationary seal 92 provides astationary seal against the pump shaft 30. In some embodiments, theannular stationary seal 92 may include an O-ring seal and/or anenergized lip seal (e.g., a lip seal including a spring). In someembodiments, the stationary seal 92 may be capable of providing amaximum seal pressure ranging from about 30 pounds per square inch (psi)to about 75 psi (e.g., about 50 psi) and/or a minimum (vacuum) pressureranging from about minus 5 psi to about minus 40 psi (e.g., about minus20 psi). As shown in FIG. 7, the second housing face 88 may also atleast partially define an annular face seal recess 94 having a secondinner diameter greater than the first inner diameter and configured toreceive therein a stationary face seal 96. In some embodiments, thestationary face seal 96 may be formed from one or more metals, ceramics,and/or mechanical carbons, such as, for example, silicon carbide,tungsten carbide, and/or carbon graphite, and may include asubstantially planar annular face configured to contact a rotating faceseal, as explained below. As shown in FIG. 7, the one or more recoveryports 74 may extend (e.g., radially) from one or more of the first sealrecess 90 or the face seal recess 94 to an exterior of the annular sealhousing 80, for example, as explained previously herein.

As shown in FIG. 7, the mechanical seal 14 includes the stationary seal92 received in the annular first seal recess 90, and the stationary faceseal 96 is received in the annular face seal recess 94. In someembodiments, the fit between the stationary seal 92 and the annularfirst seal recess 90 is such that the stationary seal 92 does not rotatewith the pump shaft 30. In some embodiments, the fit between thestationary face seal 96 and the annular face seal recess 94 is such thatthe stationary face seal 96 does not rotate with the pump shaft 30.

As shown in FIG. 7, some embodiments of the mechanical seal 14 may alsoinclude an inner sleeve 98 coupled to the annular seal housing 80 andreceiving therethrough the pump shaft 30. In some embodiments, the fitbetween an inner diameter of the inner sleeve 98 and the pump shaft maybe such that the inner sleeve 98 may substantially rotate with the pumpshaft 30, for example, such that the inner sleeve 98 rotates relative tothe annular seal housing 80. In some embodiments, the inner sleeve 98may include a substantially hollow cylindrical body defining an internalrecess 100 configured to receive therein a shaft seal 102 (e.g., anO-ring seal) configured to abut the pump shaft 30 and substantiallyrotate with the pump shaft 30.

As shown in FIG. 7, some embodiments of the mechanical seal 14 mayfurther include a rotating face seal retainer 104 configured to receivetherein a rotating face seal 106. For example, the rotating face seal106 may be received in the rotating face seal retainer 104 and may beconfigured to abut against the stationary face seal 96 and substantiallyrotate with the pump shaft 30, such that the stationary face seal 96 andthe rotating face seal 106 form a sliding seal interface therebetween.For example, the rotating face seal 106 may be formed from one or moremetals, ceramics, and/or mechanical carbons, such as, for example,silicon carbide, tungsten carbide, and/or carbon graphite, and mayinclude a substantially planar annular face configured to contact andslide relative to a corresponding substantially planar annular face ofthe stationary face seal 96, thereby forming a sliding seal interface108. The planar annular faces may be formed from a relatively hardenedmaterial and/or a relatively low friction material to slow wear rates.Through use, however, the planar annular faces may wear to an extent towhich material being pumped by the axial flow pump 12 may pass or leakthrough the sliding seal interface 108 to a point above the barrier 60and into the outer housing 66 of the axial flow pump 14. In someembodiments, as mentioned previously herein, the one or more recoveryports 74 may reduce or prevent collection of material that passesthrough the sliding seal interface 108 (and/or material passing throughthe mechanical seal 14 in general) on top of the barrier 60 in the outerhousing 66. In some embodiments, this may reduce the need forunanticipated service or replacement associated with the mechanical seal14, in some instances, prolonging the useful service life of themechanical seal 14. As shown in FIG. 7, the mechanical seal 14 may alsoinclude a biasing member 110 positioned to press the rotating face seal106 against the stationary face seal 96, for example, to improve thesealing ability of the sliding seal interface 108.

As shown in FIG. 7, some embodiments of the mechanical seal 14 mayinclude a biasing member retainer 112 radially exterior relative to thebiasing member 110 and extending substantially from a first end of theinner sleeve 98 toward the rotating face seal 106. In some embodiments,the inner sleeve 98 may be radially interior relative to the biasingmember 110. The mechanical seal 14 may also include a preload spacer 114positioned along the pump shaft 30 longitudinally opposite the biasingmember 110 relative to the seal housing 80. The preload spacer 114 maybe configured to provide a preload urging the stationary face seal 96and the rotating face seal 106 against one another, for example, bypartially compressing the biasing member 110, so that the biasing member110 provides a force against the rotating face seal 106 toward thestationary face seal 96.

As shown in FIG. 7, the mechanical seal 14 may also include a shaftcollar 116 coupled to the pump shaft 30 (e.g., via one or more setscrews), for example, to substantially maintain the longitudinalposition of the mechanical seal 14 relative to the pump shaft 30. Theshaft collar 116 may be positioned longitudinally opposite the biasingmember 110 relative to the seal housing 80.

The foregoing description generally illustrates and describes variousembodiments of the present disclosure. It will, however, be understoodby those skilled in the art that various changes and modifications canbe made to the above-discussed construction of the present disclosurewithout departing from the spirit and scope of the embodiments asdisclosed herein, and that it is intended that all matter contained inthe above description or shown in the accompanying drawings shall beinterpreted as being illustrative, and not to be taken in a limitingsense. Furthermore, the scope of the present disclosure shall beconstrued to cover various modifications, combinations, additions,alterations, etc., above and to the above-described embodiments, whichshall be considered to be within the scope of the present disclosure.Accordingly, various features and characteristics of the presentdisclosure as discussed herein may be selectively interchanged andapplied to other illustrated and non-illustrated embodiments of thedisclosure, and numerous variations, modifications, and additionsfurther can be made thereto without departing from the spirit and scopeof the present disclosure as set forth in the appended claims.

What is claimed is:
 1. A mechanical seal for an axial flow pump, themechanical seal comprising: an annular seal housing configured to bereceived in a pump housing, the annular seal housing defining a shaftaperture configured for passage therethrough by a pump shaft of theaxial flow pump, the annular seal housing comprising: a first sealhousing face; a second seal housing face opposite the first seal housingface and at least partially defining: an annular first seal recesshaving a first inner diameter and configured to receive therein anannular stationary seal, such that the annular stationary seal providesa stationary seal against the pump shaft; an annular face seal recesshaving a second inner diameter greater than the first inner diameter andconfigured to receive therein a stationary face seal; and a recoveryport extending from one or more of the first seal recess or the faceseal recess to an exterior of the annular seal housing; a stationaryseal received in the annular first seal recess; a stationary face sealreceived in the annular face seal recess; an inner sleeve coupled to theannular seal housing and configured to receive therethrough the pumpshaft and rotate with the pump shaft, such that the inner sleeve rotatesrelative to the annular seal housing, the inner sleeve comprising asubstantially hollow cylindrical body defining an internal recessconfigured to receive therein a shaft seal configured to abut the pumpshaft and rotate with the pump shaft; a rotating face seal retainerconfigured to receive therein a rotating face seal; a rotating face sealreceived in the rotating face seal retainer and configured to abutagainst the stationary face seal and rotate with the pump shaft, suchthat the stationary face seal and the rotating face seal form a slidingseal interface; and a biasing member positioned to press the rotatingface seal against the stationary face seal.
 2. The mechanical seal ofclaim 1, wherein the recovery port extends radially outward relative tothe one or more of the first seal recess or the face seal recess.
 3. Themechanical seal of claim 1, wherein the recovery port is positioned suchthat fluid passing the rotating face seal and the stationary face sealflows into the recovery port and away from the mechanical seal.
 4. Themechanical seal of claim 1, further comprising a biasing member retainerradially exterior relative to the biasing member and extendingsubstantially from a first end of the inner sleeve toward the rotatingface seal.
 5. The mechanical seal of claim 4, wherein the inner sleeveis radially interior relative to the biasing member.
 6. The mechanicalseal of claim 1, further comprising a preload spacer longitudinallyopposite the biasing member relative to the seal housing.
 7. Themechanical seal of claim 1, further comprising a shaft collar configuredto be coupled to the pump shaft, the shaft collar being longitudinallyopposite the biasing member relative to the seal housing.
 8. Themechanical seal of claim 1, wherein the seal housing further defines avent port extending from one or more of the first seal recess or theface seal recess to the exterior of the annular seal housing.
 9. Themechanical seal of claim 8, wherein the vent port extends radiallyoutward relative to the one or more of the first seal recess or the faceseal recess.
 10. The mechanical seal of claim 1, wherein one or more ofthe annular stationary seal or the shaft seal comprises one or more ofan O-ring seal or an energized lip seal.
 11. The mechanical seal ofclaim 1, wherein the recovery port is configured to be in flowcommunication with a containment chamber associated with the axial flowpump, and wherein pressure in the containment chamber is at a lowerpressure than pressure at the discharge passage of the axial flow pump,thereby creating a suction pressure at the recovery port.
 12. Themechanical seal of claim 1, wherein the annular stationary seal isconfigured to provide one or more of a maximum seal pressure rangingfrom about 30 pounds per square inch (psi) to about 75 psi or a minimumpressure ranging from about minus 5 psi to about minus 40 psi.
 13. Anaxial flow pump and mechanical seal assembly comprising: an axial flowpump configured to pump fluid, the axial flow pump comprising: alongitudinal containment chamber; a pump shaft extending longitudinallywithin the containment chamber; at least one pump housing coupled to anentry end of the pump shaft, such that the pump shaft rotates relativeto the at least one pump housing; at least one impeller coupled to thepump shaft and configured to rotate with the pump shaft; and a dischargepassage at a discharge end of the axial flow pump opposite the entry endof the pump shaft; and a mechanical seal coupled to the pump shaftopposite the entry end of the pump shaft relative to discharge passage,the mechanical seal comprising: an annular seal housing received in oneof the at least one pump housings, the annular seal housing defining ashaft aperture through which the pump shaft of the axial flow pumppasses, the annular seal housing comprising: a first seal housing face;a second seal housing face opposite the first seal housing face and atleast partially defining: an annular first seal recess having a firstinner diameter and configured to receive therein an annular stationaryseal, such that the annular stationary seal provides a stationary sealagainst the pump shaft; an annular face seal recess having a secondinner diameter greater than the first inner diameter and configured toreceive therein a stationary face seal; and a recovery port extendingfrom one or more of the first seal recess or the face seal recess to anexterior of the annular seal housing; a stationary seal received in theannular first seal recess; a stationary face seal received in theannular face seal recess; an inner sleeve coupled to the annular sealhousing and receiving therethrough the pump shaft and configured torotate with the pump shaft, such that the inner sleeve rotates relativeto the annular seal housing, the inner sleeve comprising a substantiallyhollow cylindrical body defining an internal recess configured toreceive therein a shaft seal configured to abut the pump shaft androtate with the pump shaft; a rotating face seal retainer configured toreceive therein a rotating face seal; a rotating face seal received inthe rotating face seal retainer and configured to abut against thestationary face seal and rotate with the pump shaft, such that thestationary face seal and the rotating face seal form a sliding sealinterface; and a biasing member positioned to press the rotating faceseal against the stationary face seal.
 14. The assembly of claim 13,wherein the axial flow pump is configured to extend downward into abarge interior, the longitudinal containment chamber defining a portconfigured to be coupled to a conduit of the barge to receivetherethrough fluid from the barge interior.
 15. The assembly of claim13, wherein the axial flow pump comprises a vertical barge pump.
 16. Theassembly of claim 13, wherein the axial flow pump comprises a mountingflange configured to be coupled to a support surface of a barge.
 17. Theassembly of claim 13, wherein the recovery port provides fluid flowbetween the one or more of the first seal recess or the face seal recessto an interior of the longitudinal containment chamber of the axial flowpump.
 18. The assembly of claim 13, wherein the seal housing furtherdefines a vent port extending from one or more of the first seal recessor the face seal recess to the exterior of the annular seal housing. 19.The assembly of claim 18, wherein the vent port provides fluid flowbetween the one or more of the first seal recess or the face seal recessand the barge interior.
 20. The assembly of claim 13, wherein therecovery port extends radially outward relative to the one or more ofthe first seal recess or the face seal recess.
 21. The assembly of claim13, wherein the recovery port is positioned such that fluid passing therotating face seal and the stationary face seal flows into the recoveryport and away from the mechanical seal.
 22. The assembly of claim 13,further comprising biasing member retainer radially exterior relative tothe biasing member and extending substantially from a first end of theinner sleeve toward the rotating face seal.
 23. The assembly of claim22, wherein the inner sleeve is radially interior relative to thebiasing member.
 24. The assembly of claim 13, further comprising apreload spacer longitudinally opposite the biasing member relative tothe seal housing.
 25. The assembly of claim 13, further comprising ashaft collar coupled to the pump shaft, the shaft collar beinglongitudinally opposite the biasing member relative to the seal housing.26. The assembly of claim 13, wherein the seal housing further defines avent port extending from one or more of the first seal recess or theface seal recess to the exterior of the annular seal housing.
 27. Theassembly of claim 26, wherein the vent port extends radially outwardrelative to the one or more of the first seal recess or the face sealrecess.
 28. The assembly of claim 13, wherein one or more of the annularstationary seal or the shaft seal comprises one or more of an O-ringseal or an energized lip seal.
 29. The assembly of claim 13, wherein therecovery port is in flow communication with a containment chamberassociated with the axial flow pump, and wherein pressure in thecontainment chamber is at a lower pressure than pressure at thedischarge passage of the axial flow pump, thereby creating a suctionpressure at the recovery port.
 30. The assembly of claim 13, wherein theannular stationary seal is configured to provide one or more of amaximum seal pressure ranging from about 30 pounds per square inch (psi)to about 75 psi or a minimum pressure ranging from about minus 5 psi toabout minus 40 psi.